Predictive Accuracy of Intraocular Lens Power Calculation Formulas for Cataract Surgery in Keratoconus: A Systematic...

Area of Science:

• Ophthalmology
• Biomedical Engineering

Background:

• Keratoconus (KCN) significantly alters corneal curvature.
• This corneal irregularity complicates intraocular lens (IOL) power calculations for cataract surgery.
• Traditional IOL formulas often lead to refractive errors in KCN patients.

Purpose of the Study:

• To compare the predictive accuracy of various IOL power calculation formulas in KCN patients.
• To evaluate formula performance based on mean prediction error (MPE), mean absolute error (MAE), and refractive outcomes within ±0.50 D and ±1.00 D.
• To identify the most reliable formulas for cataract surgery in eyes with keratoconus.

Main Methods:

• A systematic literature search was conducted across MEDLINE, Embase, and Cochrane databases.
• Seven studies involving 530 eyes were included in a Bayesian network meta-analysis (NMA).
• Formulas were ranked, and subgroup analyses considered KCN severity using Amsler-Krumeich criteria.

Main Results:

• Barrett True-K (Measured/Predicted) and Kane Keratoconus formulas exhibited the highest predictive accuracy.
• SRK/T performed well in moderate KCN, while Barrett True-K Predicted was favorable in mild KCN.
• Conventional formulas like Hoffer Q and Holladay showed lower accuracy, particularly in advanced KCN.

Conclusions:

• Keratoconus-specific formulas, notably Barrett True-K and Kane Keratoconus, are superior for IOL power calculation in KCN patients.
• Traditional formulas underperform, especially in severe KCN, and should be used cautiously.
• Prioritizing keratoconus-specific formulas is recommended for improved clinical outcomes, though further research with larger, standardized data is needed.